//
// Copyright (c) 2010 Luís Reis
//
// MIT License
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
using System;
using System.Collections.Generic;

namespace Pine.Core
{
	public class BlockScope : IScope
	{
		private IScope Parent;
		private IDictionary<string, Value> values = new Dictionary<string, Value>();
		
		public BlockScope(IScope parent) {
			Parent = parent;
		}
		
		public BlockScope ()
		{
		}
		
		public void Declare(bool isConst, string name, Value defaultValue) {
			if (values.ContainsKey(name))
				throw new PineException("A variable named " + name + " already exists in the scope.");
			else
				values[name] = defaultValue;
		}
		
		public Value GetItem(string key)
		{
			if (!values.ContainsKey(key)) {
				if (Parent != null) {
					return Parent.GetItem(key);
				}
				else
					throw new PineException("No variable with name " + key);
			}
			return values[key];
		}
		
		public void SetItem(string key, Value value) {
			if (values.ContainsKey(key)) {
				values[key] = value;
			}
			else {
				if (Parent != null)
					Parent.SetItem(key, value);
				else
					throw new PineException("No variable with name " + key);
			}
		}
		
		public bool Has(string name) {
			return values.ContainsKey(name) || (Parent != null && Parent.Has(name));	
		}
	}
}

